1. Field of the Invention
The present invention relates to an image forming apparatus capable of performing a cleaning control in which toner (developer) collected by cleaning rollers is transferred to a belt (transfer device) through photoconductor drums (image carriers) and collected by a cleaning device.
2. Description of Related Art
Conventionally, there is known an image forming apparatus comprising a plurality of photoconductor drums, a plurality of cleaning rollers each of which is adjacent to a corresponding photoconductor drum and configured to collect toner adhering to the surface of the corresponding photoconductor drum, a rotatable endless belt arranged opposite the photoconductor drums, a plurality of transfer rollers each of which is arranged opposite the corresponding photoconductor drum with the belt interposed therebetween, and a cleaning device for collecting toner adhering to the belt. In this image forming apparatus, a printing control and a cleaning control can be performed.
More specifically, in the printing control, a transfer current is applied between each of the photoconductor drums and the belt (the corresponding transfer roller) so that toner images carried on the photoconductor drums are transferred onto a recording sheet conveyed on the belt. In the cleaning control, a transfer current which has substantially the same magnitude as that in the printing control is applied between each of the photoconductor drums and the belt, and further an electric current is applied between each of the photoconductor drums and the corresponding cleaning roller so that toner collected by the cleaning rollers is transferred to the belt through the photoconductor drums and collected by the cleaning device.